BaseEqualsVisitor.java

/*
 * Copyright 2000-2017 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.siyeh.ig.bugs;

import com.intellij.psi.*;
import com.intellij.util.ObjectUtils;
import com.siyeh.ig.BaseInspectionVisitor;
import com.siyeh.ig.callMatcher.CallMatcher;
import com.siyeh.ig.psiutils.ExpressionUtils;
import org.jetbrains.annotations.NotNull;

/**
 * @author Bas Leijdekkers
 * @author Tagir Valeev
 */
abstract class BaseEqualsVisitor extends BaseInspectionVisitor
{
  private static final CallMatcher OBJECT_EQUALS =
    CallMatcher.instanceCall(CommonClassNames.JAVA_LANG_OBJECT, "equals").parameterTypes(CommonClassNames.JAVA_LANG_OBJECT);
  private static final CallMatcher STATIC_EQUALS =
    CallMatcher.anyOf(
      CallMatcher.staticCall("java.util.Objects", "equals").parameterCount(2),
      CallMatcher.staticCall("com.google.common.base.Objects", "equal").parameterCount(2));

  @Override
  public void visitMethodReferenceExpression(PsiMethodReferenceExpression expression) {
    super.visitMethodReferenceExpression(expression);
    if (!OBJECT_EQUALS.methodReferenceMatches(expression) && !STATIC_EQUALS.methodReferenceMatches(expression)) return;
    PsiMethod method = ObjectUtils.tryCast(expression.resolve(), PsiMethod.class);
    if (method == null) return;
    PsiType functionalInterfaceType = expression.getFunctionalInterfaceType();
    if (functionalInterfaceType == null) return;
    PsiType type1, type2;
    PsiExpression qualifier = expression.getQualifierExpression();
    type1 = LambdaUtil.getLambdaParameterFromType(functionalInterfaceType, 0);
    if (qualifier == null ||
        qualifier instanceof PsiReferenceExpression && ((PsiReferenceExpression)qualifier).isReferenceTo(method.getContainingClass())) {
      type2 = LambdaUtil.getLambdaParameterFromType(functionalInterfaceType, 1);
    }
    else {
      type2 = qualifier.getType();
    }
    checkTypes(expression, type1, type2);
  }

  @Override
  public void visitMethodCallExpression(@NotNull PsiMethodCallExpression expression) {
    super.visitMethodCallExpression(expression);
    boolean staticEqualsCall;
    if (OBJECT_EQUALS.test(expression)) {
      staticEqualsCall = false;
    }
    else if (STATIC_EQUALS.test(expression)) {
      staticEqualsCall = true;
    }
    else {
      return;
    }
    final PsiExpression[] arguments = expression.getArgumentList().getExpressions();
    final PsiExpression expression1 = arguments[0];
    final PsiExpression expression2;
    if (staticEqualsCall) {
      expression2 = arguments[1];
    }
    else {
      expression2 = ExpressionUtils.getQualifierOrThis(expression.getMethodExpression());
    }

    checkTypes(expression.getMethodExpression(), expression1.getType(), expression2.getType());
  }

  abstract void checkTypes(PsiReferenceExpression expression, PsiType type1, PsiType type2);
}